Answer: x=10
Explanation:
We can use the pythagorean theorem here: a^2 + b^2 = c^2, where c is the hypotenuse.
The values for c and one of the legs are already given, so we can plug them into the equation to find the length of the other leg x:
(square root of 200)^2 + x^2 = (square root of 300)^2
200 + x^2 = 300
x^2 = 100
x = 10